Used 450 - What to replace

[TBucket32]

Someone needs to find a cure for this helicopter virus. It keeps eating through my wallet! I only started flying in Feb and I'm already up to 4 helis.

I just picked up a used Align 450 Plus DFC. Looks to be in pretty good condition just missing the FBL controller...got a really good deal. I'm planning on putting in a ZYX-S2 over the winter when funds allow.

Since this is a used heli, I'm planning to do a full tear down to inspect for any hidden problems and also learn the build and setup process. I will replace anything that seems questionable. But my question is: Is there any parts that you would automatically replace, sight unseen, no matter the condition, if you buy a used machine? For example, would you automatically replace main and head bearings since you don't know their past? What about a main shaft? Is it a given to replace that no matter what?

I know this forum is full of people with the same disease that I now have. Your opinions (and maybe some coping mechanisms) would be greatly appreciated.

[CrashNburn420]

I would check all the bearings and replace any that notchy at all. Maybe replace the belt with a new one.

The zyx is an ok gyro, I had a few of them at one point. Keep an eye on the classifieds you can get some decent deals on uses gyros.

[islrcr1]

Nice purchase, bought one last spring. Tore it apart and rebuilt it. No loktight or grease anywhere. A great flying heli, wouldn't change a thing.

[Helique]

If you don't already have them, get a high quality set of hex wrenches. Search HF for brand names. Good quality wrenches make all the difference when it comes to your rebuild. Don't get crazy with the thread lock - a little touch is all that is needed. Remember, no thread lock on screws going into plastic parts. No need to change the main shaft unless of course it's bent. Check all shafts, tail boom and torque tube for straightness. Check bearings for smoothness and lube. Make sure you assemble the main frame on a flat surface and that everything is square before you tighten everything up.

[ticedoff8]

For example, would you automatically replace main and head bearings since you don't know their past? What about a main shaft? Is it a given to replace that no matter what?

Nope.
There are no parts that I would replace as "a given".

If you don't know anything about the heli, the teardown / rebuild process can lead you to areas where you may want to focus more closely.

Previous crashes will cause tail rotor shafts, feathering shafts and main masts to be bent.
They will also destroy the bearings in the motor, chip teeth on the servo gears and destroy bearings in the main & tail rotor blade grips (radial & thrust).
Depending on who built it, it may be missing blue LocTite on many of the screws that hold the head and tail rotor together.

Plus, the first few flight will tell you a lot about things you may have missed.

Buying a used heli is a crap shoot.

Out of the 12 helicopters I have owned, only 1 was "brand new" and I built it out of the box.

[Helique]

Originally Posted by ticedoff8

...buying a used heli is a crap shoot.

+1 on that!
All of my helis were bought used on ebay and all of them had issues the seller either didn't reveal or didn't know about.

[Dan MacKay]

Hi TB,
As you are tearing this down completely a couple of things can be your friend. Get yourself a piece of glass and a servo tester (if you don't already have one). When you do your tear down check the feathering shaft and main shaft for true. If they are then they are good to go. If the feathering shaft is bent then replace it. Personally I would replace the grip and throw-out bearings as well. They are cheap and easy to replace. If the main shaft is bent of course replace it and I would seriously consider replacing the main bearings. (5mm x 11mm x 5mm) Either order factory replacements or pick them up in bulk at the pretty near any hobby shop. Bulk is cheaper and you should always have a couple of spare.

As was mentioned earlier check the main drive very carefully for missing teeth and wear. Replace as necessary.

Make sure the torque tube teeth are all in order.

I would replace the tail rotor shaft just as a matter of course. They are so fragile that I have yet so see many that survive more that a few flights without touching grass. They can bend so very slightly but if it is it will set a slight vibration, and FBL controllers do not like vibration.

Check the swash plate for slop and or damage. There should be no slop where the collar fits the shaft and it should tilt in all directions with no play.

Check all ball links for fit. If they are sloppy replace them making sure the "A" is on the out side.

Pull all your servos and toss them on a servo tester just to be sure. If one is bad you may have to replace the dead one with one that is exactly like the remaining ones. Anyone correct me if I am wrong as I am not familiar with the XYZ FBL controller. I only use Ikons and they do not like mis-matched servos.

Wash all your screws and hex heads in rubbing alcohol to clean them, use blue locktite for all metal to metal and you should be good to go.

You should be good to go after that. If you have all the parts available then you can likely get all the mechanical stuff done in an afternoon.

Dan